/* SPDX-License-Identifier: MIT */ /* this is a pretty robust parser for EDID, and we're tasked with parsing * an arbitrary panel. We will pass it a raw EDID block and a struct which * it must fill in with values. The set of values we need is pretty limited * at present. */ #include #include #include #include #include #include #include #include struct edid_context { int claims_one_point_oh; int claims_one_point_two; int claims_one_point_three; int claims_one_point_four; int nonconformant_digital_display; int nonconformant_extension; int did_detailed_timing; int has_name_descriptor; int has_range_descriptor; int has_preferred_timing; int has_valid_checksum; int has_valid_cvt; int has_valid_dummy_block; int has_valid_week; int has_valid_year; int has_valid_detailed_blocks; int has_valid_extension_count; int has_valid_descriptor_ordering; int has_valid_descriptor_pad; int has_valid_range_descriptor; int has_valid_max_dotclock; int has_valid_string_termination; int manufacturer_name_well_formed; int seen_non_detailed_descriptor; int warning_excessive_dotclock_correction; int warning_zero_preferred_refresh; enum edid_status conformant; }; /* Stuff that isn't used anywhere but is nice to pretty-print while we're decoding everything else. */ static struct { unsigned int model; unsigned int serial; unsigned int year; unsigned int week; unsigned int version[2]; unsigned int nonconformant; unsigned int type; unsigned int x_mm; unsigned int y_mm; unsigned int voltage; unsigned int sync; const char *syncmethod; const char *range_class; const char *stereo; } extra_info; static struct edid tmp_edid; static int manufacturer_name(unsigned char *x, char *output) { output[0] = ((x[0] & 0x7C) >> 2) + '@'; output[1] = ((x[0] & 0x03) << 3) + ((x[1] & 0xE0) >> 5) + '@'; output[2] = (x[1] & 0x1F) + '@'; output[3] = 0; if (isupper(output[0]) && isupper(output[1]) && isupper(output[2])) return 1; memset(output, 0, 4); return 0; } static int detailed_cvt_descriptor(unsigned char *x, int first) { const unsigned char empty[3] = { 0, 0, 0 }; static const char *names[] = { "50", "60", "75", "85" }; int width = 0, height = 0; int valid = 1; int fifty = 0, sixty = 0, seventyfive = 0, eightyfive = 0, reduced = 0; if (!first && !memcmp(x, empty, 3)) return valid; height = x[0]; height |= (x[1] & 0xf0) << 4; height++; height *= 2; switch (x[1] & 0x0c) { case 0x00: width = (height * 4) / 3; break; case 0x04: width = (height * 16) / 9; break; case 0x08: width = (height * 16) / 10; break; case 0x0c: width = (height * 15) / 9; break; } if (x[1] & 0x03) valid = 0; if (x[2] & 0x80) valid = 0; if (!(x[2] & 0x1f)) valid = 0; fifty = (x[2] & 0x10); sixty = (x[2] & 0x08); seventyfive = (x[2] & 0x04); eightyfive = (x[2] & 0x02); reduced = (x[2] & 0x01); if (!valid) { printk(BIOS_SPEW, " (broken)\n"); } else { printk(BIOS_SPEW, " %dx%d @ (%s%s%s%s%s) Hz (%s%s preferred)\n", width, height, fifty ? "50 " : "", sixty ? "60 " : "", seventyfive ? "75 " : "", eightyfive ? "85 " : "", reduced ? "60RB " : "", names[(x[2] & 0x60) >> 5], (((x[2] & 0x60) == 0x20) && reduced) ? "RB" : ""); } return valid; } /* extract a CP437 string from a detailed subblock, checking for termination (if * less than len of bytes) with LF and padded with SP. */ static char * extract_string(unsigned char *x, int *valid_termination, int len) { static char ret[EDID_ASCII_STRING_LENGTH + 1]; int i, seen_newline = 0; memset(ret, 0, sizeof(ret)); for (i = 0; i < MIN(len, EDID_ASCII_STRING_LENGTH); i++) { if (seen_newline) { if (x[i] != 0x20) { *valid_termination = 0; return ret; } } else if (x[i] == 0x0a) { seen_newline = 1; } else { /* normal characters */ ret[i] = x[i]; } } return ret; } /* 1 means valid data */ static int detailed_block(struct edid *result_edid, unsigned char *x, int in_extension, struct edid_context *c) { struct edid *out = &tmp_edid; int i; if (console_log_level(BIOS_SPEW)) { printk(BIOS_SPEW, "Hex of detail: "); for (i = 0; i < 18; i++) printk(BIOS_SPEW, "%02x", x[i]); printk(BIOS_SPEW, "\n"); } /* Result might already have some valid fields like mode_is_supported */ *out = *result_edid; if (x[0] == 0 && x[1] == 0) { /* Monitor descriptor block, not detailed timing descriptor. */ if (x[2] != 0) { /* 1.3, 3.10.3 */ printk(BIOS_SPEW, "Monitor descriptor block has byte 2 nonzero (0x%02x)\n", x[2]); c->has_valid_descriptor_pad = 0; } if (x[3] != 0xfd && x[4] != 0x00) { /* 1.3, 3.10.3 */ printk(BIOS_SPEW, "Monitor descriptor block has byte 4 nonzero (0x%02x)\n", x[4]); c->has_valid_descriptor_pad = 0; } c->seen_non_detailed_descriptor = 1; if (x[3] <= 0xF) { /* * in principle we can decode these, if we know what * they are. * 0x0f seems to be common in laptop panels. * 0x0e is used by EPI: http://www.epi-standard.org/ */ printk(BIOS_SPEW, "Manufacturer-specified data, tag %d\n", x[3]); return 1; } switch (x[3]) { case 0x10: printk(BIOS_SPEW, "Dummy block\n"); for (i = 5; i < 18; i++) if (x[i] != 0x00) c->has_valid_dummy_block = 0; return 1; case 0xF7: /* TODO */ printk(BIOS_SPEW, "Established timings III\n"); return 1; case 0xF8: { int valid_cvt = 1; /* just this block */ printk(BIOS_SPEW, "CVT 3-byte code descriptor:\n"); if (x[5] != 0x01) { c->has_valid_cvt = 0; return 0; } for (i = 0; i < 4; i++) valid_cvt &= detailed_cvt_descriptor(x + 6 + (i * 3), (i == 0)); c->has_valid_cvt &= valid_cvt; return 1; } case 0xF9: /* TODO */ printk(BIOS_SPEW, "Color management data\n"); return 1; case 0xFA: /* TODO */ printk(BIOS_SPEW, "More standard timings\n"); return 1; case 0xFB: /* TODO */ printk(BIOS_SPEW, "Color point\n"); return 1; case 0xFC: printk(BIOS_SPEW, "Monitor name: %s\n", extract_string(x + 5, &c->has_valid_string_termination, EDID_ASCII_STRING_LENGTH)); c->has_name_descriptor = 1; return 1; case 0xFD: { int h_max_offset = 0, h_min_offset = 0; int v_max_offset = 0, v_min_offset = 0; int is_cvt = 0; c->has_range_descriptor = 1; extra_info.range_class = ""; /* * XXX todo: implement feature flags, vtd blocks * XXX check: ranges are well-formed; block termination * if no vtd */ if (c->claims_one_point_four) { if (x[4] & 0x02) { v_max_offset = 255; if (x[4] & 0x01) v_min_offset = 255; } if (x[4] & 0x04) { h_max_offset = 255; if (x[4] & 0x03) h_min_offset = 255; } } else if (x[4]) { c->has_valid_range_descriptor = 0; } /* * despite the values, this is not a bitfield. */ switch (x[10]) { case 0x00: /* default gtf */ extra_info.range_class = "GTF"; break; case 0x01: /* range limits only */ extra_info.range_class = "bare limits"; if (!c->claims_one_point_four) c->has_valid_range_descriptor = 0; break; case 0x02: /* secondary gtf curve */ extra_info.range_class = "GTF with icing"; break; case 0x04: /* cvt */ extra_info.range_class = "CVT"; is_cvt = 1; if (!c->claims_one_point_four) c->has_valid_range_descriptor = 0; break; default: /* invalid */ c->has_valid_range_descriptor = 0; extra_info.range_class = "invalid"; break; } if (x[5] + v_min_offset > x[6] + v_max_offset) c->has_valid_range_descriptor = 0; if (x[7] + h_min_offset > x[8] + h_max_offset) c->has_valid_range_descriptor = 0; printk(BIOS_SPEW, "Monitor ranges (%s): %d-%dHz V, %d-%dkHz H", extra_info.range_class, x[5] + v_min_offset, x[6] + v_max_offset, x[7] + h_min_offset, x[8] + h_max_offset); if (x[9]) printk(BIOS_SPEW, ", max dotclock %dMHz\n", x[9] * 10); else { if (c->claims_one_point_four) c->has_valid_max_dotclock = 0; printk(BIOS_SPEW, "\n"); } if (is_cvt) { int max_h_pixels = 0; printk(BIOS_SPEW, "CVT version %d.%d\n", x[11] & 0xf0 >> 4, x[11] & 0x0f); if (x[12] & 0xfc) { int raw_offset = (x[12] & 0xfc) >> 2; printk(BIOS_SPEW, "Real max dotclock: %dKHz\n", (x[9] * 10000) - (raw_offset * 250)); if (raw_offset >= 40) c->warning_excessive_dotclock_correction = 1; } max_h_pixels = x[12] & 0x03; max_h_pixels <<= 8; max_h_pixels |= x[13]; max_h_pixels *= 8; if (max_h_pixels) printk(BIOS_SPEW, "Max active pixels per line: %d\n", max_h_pixels); printk(BIOS_SPEW, "Supported aspect ratios: %s %s %s %s %s\n", x[14] & 0x80 ? "4:3" : "", x[14] & 0x40 ? "16:9" : "", x[14] & 0x20 ? "16:10" : "", x[14] & 0x10 ? "5:4" : "", x[14] & 0x08 ? "15:9" : ""); if (x[14] & 0x07) c->has_valid_range_descriptor = 0; printk(BIOS_SPEW, "Preferred aspect ratio: "); switch ((x[15] & 0xe0) >> 5) { case 0x00: printk(BIOS_SPEW, "4:3"); break; case 0x01: printk(BIOS_SPEW, "16:9"); break; case 0x02: printk(BIOS_SPEW, "16:10"); break; case 0x03: printk(BIOS_SPEW, "5:4"); break; case 0x04: printk(BIOS_SPEW, "15:9"); break; default: printk(BIOS_SPEW, "(broken)"); break; } printk(BIOS_SPEW, "\n"); if (x[15] & 0x04) printk(BIOS_SPEW, "Supports CVT standard blanking\n"); if (x[15] & 0x10) printk(BIOS_SPEW, "Supports CVT reduced blanking\n"); if (x[15] & 0x07) c->has_valid_range_descriptor = 0; if (x[16] & 0xf0) { printk(BIOS_SPEW, "Supported display scaling:\n"); if (x[16] & 0x80) printk(BIOS_SPEW, " Horizontal shrink\n"); if (x[16] & 0x40) printk(BIOS_SPEW, " Horizontal stretch\n"); if (x[16] & 0x20) printk(BIOS_SPEW, " Vertical shrink\n"); if (x[16] & 0x10) printk(BIOS_SPEW, " Vertical stretch\n"); } if (x[16] & 0x0f) c->has_valid_range_descriptor = 0; if (x[17]) printk(BIOS_SPEW, "Preferred vertical refresh: %d Hz\n", x[17]); else c->warning_zero_preferred_refresh = 1; } /* * Slightly weird to return a global, but I've never * seen any EDID block with two range descriptors, so * it's harmless. */ return 1; } case 0xFE: /* * TODO: Two of these in a row, in the third and fourth * slots, seems to be specified by SPWG: * http://www.spwg.org/ */ strcpy(result_edid->ascii_string, extract_string(x + 5, &c->has_valid_string_termination, EDID_ASCII_STRING_LENGTH)); printk(BIOS_SPEW, "ASCII string: %s\n", result_edid->ascii_string); return 1; case 0xFF: printk(BIOS_SPEW, "Serial number: %s\n", extract_string(x + 5, &c->has_valid_string_termination, EDID_ASCII_STRING_LENGTH)); return 1; default: printk(BIOS_SPEW, "Unknown monitor description type %d\n", x[3]); return 0; } } if (c->seen_non_detailed_descriptor && !in_extension) c->has_valid_descriptor_ordering = 0; /* Edid contains pixel clock in terms of 10KHz */ out->mode.pixel_clock = (x[0] + (x[1] << 8)) * 10; /* LVDS supports following pixel clocks 25000...112000 kHz: single channel 80000...224000 kHz: dual channel There is some overlap in theoretically supported pixel clock between single-channel and dual-channel. In practice with current panels all panels <= 75200 kHz: single channel >= 97750 kHz: dual channel We have no samples between those values, so put a threshold at 95000 kHz. If we get anything over 95000 kHz with single channel, we can make this more sophisticated but it's currently not needed. */ out->mode.lvds_dual_channel = (out->mode.pixel_clock >= 95000); extra_info.x_mm = (x[12] + ((x[14] & 0xF0) << 4)); extra_info.y_mm = (x[13] + ((x[14] & 0x0F) << 8)); out->mode.ha = (x[2] + ((x[4] & 0xF0) << 4)); out->mode.hbl = (x[3] + ((x[4] & 0x0F) << 8)); out->mode.hso = (x[8] + ((x[11] & 0xC0) << 2)); out->mode.hspw = (x[9] + ((x[11] & 0x30) << 4)); out->mode.hborder = x[15]; out->mode.va = (x[5] + ((x[7] & 0xF0) << 4)); out->mode.vbl = (x[6] + ((x[7] & 0x0F) << 8)); out->mode.vso = ((x[10] >> 4) + ((x[11] & 0x0C) << 2)); out->mode.vspw = ((x[10] & 0x0F) + ((x[11] & 0x03) << 4)); out->mode.vborder = x[16]; /* We assume rgb888 (32 bits per pixel) framebuffers by default. * Chipsets that want something else will need to override this with * another call to edid_set_framebuffer_bits_per_pixel(). As a cheap * heuristic, assume that X86 systems require a 64-byte row alignment * (since that seems to be true for most Intel chipsets). */ if (ENV_X86) edid_set_framebuffer_bits_per_pixel(out, 32, 64); else edid_set_framebuffer_bits_per_pixel(out, 32, 0); switch ((x[17] & 0x18) >> 3) { case 0x00: extra_info.syncmethod = " analog composite"; break; case 0x01: extra_info.syncmethod = " bipolar analog composite"; break; case 0x02: extra_info.syncmethod = " digital composite"; break; case 0x03: extra_info.syncmethod = ""; break; } out->mode.pvsync = (x[17] & (1 << 2)) ? '+' : '-'; out->mode.phsync = (x[17] & (1 << 1)) ? '+' : '-'; switch (x[17] & 0x61) { case 0x20: extra_info.stereo = "field sequential L/R"; break; case 0x40: extra_info.stereo = "field sequential R/L"; break; case 0x21: extra_info.stereo = "interleaved right even"; break; case 0x41: extra_info.stereo = "interleaved left even"; break; case 0x60: extra_info.stereo = "four way interleaved"; break; case 0x61: extra_info.stereo = "side by side interleaved"; break; default: extra_info.stereo = ""; break; } printk(BIOS_SPEW, "Detailed mode (IN HEX): Clock %d KHz, %x mm x %x mm\n" " %04x %04x %04x %04x hborder %x\n" " %04x %04x %04x %04x vborder %x\n" " %chsync %cvsync%s%s%s\n", out->mode.pixel_clock, extra_info.x_mm, extra_info.y_mm, out->mode.ha, out->mode.ha + out->mode.hso, out->mode.ha + out->mode.hso + out->mode.hspw, out->mode.ha + out->mode.hbl, out->mode.hborder, out->mode.va, out->mode.va + out->mode.vso, out->mode.va + out->mode.vso + out->mode.vspw, out->mode.va + out->mode.vbl, out->mode.vborder, out->mode.phsync, out->mode.pvsync, extra_info.syncmethod, x[17] & 0x80 ? " interlaced" : "", extra_info.stereo); if (!c->did_detailed_timing) { printk(BIOS_SPEW, "Did detailed timing\n"); c->did_detailed_timing = 1; *result_edid = *out; } return 1; } static int do_checksum(unsigned char *x) { int valid = 0; printk(BIOS_SPEW, "Checksum: 0x%hhx", x[0x7f]); { unsigned char sum = 0; int i; for (i = 0; i < 128; i++) sum += x[i]; if (sum) { printk(BIOS_SPEW, " (should be 0x%hhx)", (unsigned char)(x[0x7f] - sum)); } else { valid = 1; printk(BIOS_SPEW, " (valid)"); } } printk(BIOS_SPEW, "\n"); return valid; } /* CEA extension */ static const char * audio_format(unsigned char x) { switch (x) { case 0: return "RESERVED"; case 1: return "Linear PCM"; case 2: return "AC-3"; case 3: return "MPEG 1 (Layers 1 & 2)"; case 4: return "MPEG 1 Layer 3 (MP3)"; case 5: return "MPEG2 (multichannel)"; case 6: return "AAC"; case 7: return "DTS"; case 8: return "ATRAC"; case 9: return "One Bit Audio"; case 10: return "Dolby Digital+"; case 11: return "DTS-HD"; case 12: return "MAT (MLP)"; case 13: return "DST"; case 14: return "WMA Pro"; case 15: return "RESERVED"; } return "BROKEN"; /* can't happen */ } static void cea_audio_block(unsigned char *x) { int i, format; int length = x[0] & 0x1f; if (length % 3) { printk(BIOS_SPEW, "Broken CEA audio block length %d\n", length); /* XXX non-conformant */ return; } for (i = 1; i < length; i += 3) { format = (x[i] & 0x78) >> 3; printk(BIOS_SPEW, " %s, max channels %d\n", audio_format(format), x[i] & 0x07); printk(BIOS_SPEW, " Supported sample rates (kHz):%s%s%s%s%s%s%s\n", (x[i+1] & 0x40) ? " 192" : "", (x[i+1] & 0x20) ? " 176.4" : "", (x[i+1] & 0x10) ? " 96" : "", (x[i+1] & 0x08) ? " 88.2" : "", (x[i+1] & 0x04) ? " 48" : "", (x[i+1] & 0x02) ? " 44.1" : "", (x[i+1] & 0x01) ? " 32" : ""); if (format == 1) { printk(BIOS_SPEW, " Supported sample sizes (bits):%s%s%s\n", (x[2] & 0x04) ? " 24" : "", (x[2] & 0x02) ? " 20" : "", (x[2] & 0x01) ? " 16" : ""); } else if (format <= 8) { printk(BIOS_SPEW, " Maximum bit rate: %d kHz\n", x[2] * 8); } } } static void cea_video_block(unsigned char *x) { int i; int length = x[0] & 0x1f; for (i = 1; i < length; i++) printk(BIOS_SPEW, " VIC %02d %s\n", x[i] & 0x7f, x[i] & 0x80 ? "(native)" : ""); } static void cea_hdmi_block(struct edid *out, unsigned char *x) { int length = x[0] & 0x1f; out->hdmi_monitor_detected = 1; printk(BIOS_SPEW, " (HDMI)\n"); printk(BIOS_SPEW, " Source physical address %d.%d.%d.%d\n", x[4] >> 4, x[4] & 0x0f, x[5] >> 4, x[5] & 0x0f); if (length > 5) { if (x[6] & 0x80) printk(BIOS_SPEW, " Supports_AI\n"); if (x[6] & 0x40) printk(BIOS_SPEW, " DC_48bit\n"); if (x[6] & 0x20) printk(BIOS_SPEW, " DC_36bit\n"); if (x[6] & 0x10) printk(BIOS_SPEW, " DC_30bit\n"); if (x[6] & 0x08) printk(BIOS_SPEW, " DC_Y444\n"); /* two reserved */ if (x[6] & 0x01) printk(BIOS_SPEW, " DVI_Dual\n"); } if (length > 6) printk(BIOS_SPEW, " Maximum TMDS clock: %dMHz\n", x[7] * 5); /* XXX the walk here is really ugly, and needs to be length-checked */ if (length > 7) { int b = 0; if (x[8] & 0x80) { printk(BIOS_SPEW, " Video latency: %d\n", x[9 + b]); printk(BIOS_SPEW, " Audio latency: %d\n", x[10 + b]); b += 2; } if (x[8] & 0x40) { printk(BIOS_SPEW, " Interlaced video latency: %d\n", x[9 + b]); printk(BIOS_SPEW, " Interlaced audio latency: %d\n", x[10 + b]); b += 2; } if (x[8] & 0x20) { int mask = 0, formats = 0; int len_xx, len_3d; printk(BIOS_SPEW, " Extended HDMI video details:\n"); if (x[9 + b] & 0x80) printk(BIOS_SPEW, " 3D present\n"); if ((x[9 + b] & 0x60) == 0x20) { printk(BIOS_SPEW, " All advertised VICs are 3D-capable\n"); formats = 1; } if ((x[9 + b] & 0x60) == 0x40) { printk(BIOS_SPEW, " 3D-capable-VIC mask present\n"); formats = 1; mask = 1; } switch (x[9 + b] & 0x18) { case 0x00: break; case 0x08: printk(BIOS_SPEW, " Base EDID image size is aspect ratio\n"); break; case 0x10: printk(BIOS_SPEW, " Base EDID image size is in units of 1cm\n"); break; case 0x18: printk(BIOS_SPEW, " Base EDID image size is in units of 5cm\n"); break; } len_xx = (x[10 + b] & 0xe0) >> 5; len_3d = (x[10 + b] & 0x1f) >> 0; b += 2; if (len_xx) { printk(BIOS_SPEW, " Skipping %d bytes that HDMI refuses to publicly" " document\n", len_xx); b += len_xx; } if (len_3d) { if (formats) { if (x[9 + b] & 0x01) printk(BIOS_SPEW, " Side-by-side 3D supported\n"); if (x[10 + b] & 0x40) printk(BIOS_SPEW, " Top-and-bottom 3D supported\n"); if (x[10 + b] & 0x01) printk(BIOS_SPEW, " Frame-packing 3D supported\n"); b += 2; } if (mask) { int i; printk(BIOS_SPEW, " 3D VIC indices:"); /* worst bit ordering ever */ for (i = 0; i < 8; i++) if (x[10 + b] & (1 << i)) printk(BIOS_SPEW, " %d", i); for (i = 0; i < 8; i++) if (x[9 + b] & (1 << i)) printk(BIOS_SPEW, " %d", i + 8); printk(BIOS_SPEW, "\n"); b += 2; } /* * XXX list of nibbles: * 2D_VIC_Order_X * 3D_Structure_X * (optionally: 3D_Detail_X and reserved) */ } } /* Tell static analysis we know index b is left unused. */ (void)b; } } static void cea_block(struct edid *out, unsigned char *x) { unsigned int oui; switch ((x[0] & 0xe0) >> 5) { case 0x01: printk(BIOS_SPEW, " Audio data block\n"); cea_audio_block(x); break; case 0x02: printk(BIOS_SPEW, " Video data block\n"); cea_video_block(x); break; case 0x03: /* yes really, endianness lols */ oui = (x[3] << 16) + (x[2] << 8) + x[1]; printk(BIOS_SPEW, " Vendor-specific data block, OUI %06x", oui); if (oui == 0x000c03) cea_hdmi_block(out, x); else printk(BIOS_SPEW, "\n"); break; case 0x04: printk(BIOS_SPEW, " Speaker allocation data block\n"); break; case 0x05: printk(BIOS_SPEW, " VESA DTC data block\n"); break; case 0x07: printk(BIOS_SPEW, " Extended tag: "); switch (x[1]) { case 0x00: printk(BIOS_SPEW, "video capability data block\n"); break; case 0x01: printk(BIOS_SPEW, "vendor-specific video data block\n"); break; case 0x02: printk(BIOS_SPEW, "VESA video display device information data block\n"); break; case 0x03: printk(BIOS_SPEW, "VESA video data block\n"); break; case 0x04: printk(BIOS_SPEW, "HDMI video data block\n"); break; case 0x05: printk(BIOS_SPEW, "Colorimetry data block\n"); break; case 0x10: printk(BIOS_SPEW, "CEA miscellaneous audio fields\n"); break; case 0x11: printk(BIOS_SPEW, "Vendor-specific audio data block\n"); break; case 0x12: printk(BIOS_SPEW, "HDMI audio data block\n"); break; default: if (x[1] >= 6 && x[1] <= 15) printk(BIOS_SPEW, "Reserved video block (%02x)\n", x[1]); else if (x[1] >= 19 && x[1] <= 31) printk(BIOS_SPEW, "Reserved audio block (%02x)\n", x[1]); else printk(BIOS_SPEW, "Unknown (%02x)\n", x[1]); break; } break; default: { int tag = (*x & 0xe0) >> 5; int length = *x & 0x1f; printk(BIOS_SPEW, " Unknown tag %d, length %d (raw %02x)\n", tag, length, *x); break; } } } static int parse_cea(struct edid *out, unsigned char *x, struct edid_context *c) { int ret = 0; int version = x[1]; int offset = x[2]; unsigned char *detailed; if (version >= 1) do { if (version == 1 && x[3] != 0) ret = 1; if (offset < 4) break; if (version < 3) printk(BIOS_SPEW, "%d 8-byte timing descriptors\n", (offset - 4) / 8); else if (version == 3) { int i; printk(BIOS_SPEW, "%d bytes of CEA data\n", offset - 4); for (i = 4; i < offset; i += (x[i] & 0x1f) + 1) cea_block(out, x + i); } if (version >= 2) { if (x[3] & 0x80) printk(BIOS_SPEW, "Underscans PC formats by default\n"); if (x[3] & 0x40) printk(BIOS_SPEW, "Basic audio support\n"); if (x[3] & 0x20) printk(BIOS_SPEW, "Supports YCbCr 4:4:4\n"); if (x[3] & 0x10) printk(BIOS_SPEW, "Supports YCbCr 4:2:2\n"); printk(BIOS_SPEW, "%d native detailed modes\n", x[3] & 0x0f); } for (detailed = x + offset; detailed + 18 < x + 127; detailed += 18) if (detailed[0]) detailed_block(out, detailed, 1, c); } while (0); c->has_valid_checksum &= do_checksum(x); return ret; } /* generic extension code */ static void extension_version(struct edid *out, unsigned char *x) { printk(BIOS_SPEW, "Extension version: %d\n", x[1]); } static int parse_extension(struct edid *out, unsigned char *x, struct edid_context *c) { int conformant_extension = 0; printk(BIOS_SPEW, "\n"); switch (x[0]) { case 0x02: printk(BIOS_SPEW, "CEA extension block\n"); extension_version(out, x); conformant_extension = parse_cea(out, x, c); break; case 0x10: printk(BIOS_SPEW, "VTB extension block\n"); break; case 0x40: printk(BIOS_SPEW, "DI extension block\n"); break; case 0x50: printk(BIOS_SPEW, "LS extension block\n"); break; case 0x60: printk(BIOS_SPEW, "DPVL extension block\n"); break; case 0xF0: printk(BIOS_SPEW, "Block map\n"); break; case 0xFF: printk(BIOS_SPEW, "Manufacturer-specific extension block\n"); break; default: printk(BIOS_SPEW, "Unknown extension block\n"); break; } printk(BIOS_SPEW, "\n"); return conformant_extension; } static const struct { int x, y, refresh; } established_timings[] = { /* 0x23 bit 7 - 0 */ {720, 400, 70}, {720, 400, 88}, {640, 480, 60}, {640, 480, 67}, {640, 480, 72}, {640, 480, 75}, {800, 600, 56}, {800, 600, 60}, /* 0x24 bit 7 - 0 */ {800, 600, 72}, {800, 600, 75}, {832, 624, 75}, {1280, 768, 87}, {1024, 768, 60}, {1024, 768, 70}, {1024, 768, 75}, {1280, 1024, 75}, /* 0x25 bit 7*/ {1152, 870, 75}, }; static void print_subsection(const char *name, unsigned char *edid, int start, int end) { int i; printk(BIOS_SPEW, "%s:", name); for (i = strlen(name); i < 15; i++) printk(BIOS_SPEW, " "); for (i = start; i <= end; i++) printk(BIOS_SPEW, " %02x", edid[i]); printk(BIOS_SPEW, "\n"); } static void dump_breakdown(unsigned char *edid) { printk(BIOS_SPEW, "Extracted contents:\n"); print_subsection("header", edid, 0, 7); print_subsection("serial number", edid, 8, 17); print_subsection("version", edid, 18, 19); print_subsection("basic params", edid, 20, 24); print_subsection("chroma info", edid, 25, 34); print_subsection("established", edid, 35, 37); print_subsection("standard", edid, 38, 53); print_subsection("descriptor 1", edid, 54, 71); print_subsection("descriptor 2", edid, 72, 89); print_subsection("descriptor 3", edid, 90, 107); print_subsection("descriptor 4", edid, 108, 125); print_subsection("extensions", edid, 126, 126); print_subsection("checksum", edid, 127, 127); printk(BIOS_SPEW, "\n"); } /* * Lookup table of some well-known modes that can be useful in case the * auto-detected mode is unsuitable. * ha = hdisplay; va = vdisplay; * hbl = htotal - hdisplay; vbl = vtotal - vdisplay; * hso = hsync_start - hdsiplay; vso = vsync_start - vdisplay; * hspw = hsync_end - hsync_start; vspw = vsync_end - vsync_start; */ static struct edid_mode known_modes[NUM_KNOWN_MODES] = { [EDID_MODE_640x480_60Hz] = { .name = "640x480@60Hz", .pixel_clock = 25200, .refresh = 60, .ha = 640, .hbl = 160, .hso = 16, .hspw = 96, .va = 480, .vbl = 45, .vso = 10, .vspw = 2, .phsync = '-', .pvsync = '-' }, [EDID_MODE_720x480_60Hz] = { .name = "720x480@60Hz", .pixel_clock = 27000, .refresh = 60, .ha = 720, .hbl = 138, .hso = 16, .hspw = 62, .va = 480, .vbl = 45, .vso = 9, .vspw = 6, .phsync = '-', .pvsync = '-' }, [EDID_MODE_1280x720_60Hz] = { .name = "1280x720@60Hz", .pixel_clock = 74250, .refresh = 60, .ha = 1280, .hbl = 370, .hso = 110, .hspw = 40, .va = 720, .vbl = 30, .vso = 5, .vspw = 20, .phsync = '+', .pvsync = '+' }, [EDID_MODE_1920x1080_60Hz] = { .name = "1920x1080@60Hz", .pixel_clock = 148500, .refresh = 60, .ha = 1920, .hbl = 280, .hso = 88, .hspw = 44, .va = 1080, .vbl = 45, .vso = 4, .vspw = 5, .phsync = '+', .pvsync = '+' }, }; int set_display_mode(struct edid *edid, enum edid_modes mode) { if (mode == EDID_MODE_AUTO) return 0; if (edid->mode_is_supported[mode]) { printk(BIOS_DEBUG, "Forcing mode %s\n", known_modes[mode].name); edid->mode = known_modes[mode]; return 0; } printk(BIOS_ERR, "Requested display mode not supported.\n"); return -1; } /* * Given a raw edid block, decode it into a form * that other parts of coreboot can use -- mainly * graphics bringup functions. The raw block is * required to be 128 bytes long, per the standard, * but we have no way of checking this minimum length. * We accept what we are given. */ int decode_edid(unsigned char *edid, int size, struct edid *out) { int analog, i, j; struct edid_context c = { .has_valid_cvt = 1, .has_valid_dummy_block = 1, .has_valid_descriptor_ordering = 1, .has_valid_detailed_blocks = 1, .has_valid_descriptor_pad = 1, .has_valid_range_descriptor = 1, .has_valid_max_dotclock = 1, .has_valid_string_termination = 1, .conformant = EDID_CONFORMANT, }; if (!edid) { printk(BIOS_ERR, "No EDID found\n"); return EDID_ABSENT; } dump_breakdown(edid); if (memcmp(edid, "\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00", 8)) { printk(BIOS_ERR, "No header found\n"); return EDID_ABSENT; } memset(out, 0, sizeof(*out)); if (manufacturer_name(edid + 0x08, out->manufacturer_name)) c.manufacturer_name_well_formed = 1; extra_info.model = (unsigned short)(edid[0x0A] + (edid[0x0B] << 8)); extra_info.serial = (unsigned int)(edid[0x0C] + (edid[0x0D] << 8) + (edid[0x0E] << 16) + (edid[0x0F] << 24)); printk(BIOS_SPEW, "Manufacturer: %s Model %x Serial Number %u\n", out->manufacturer_name, (unsigned short)(edid[0x0A] + (edid[0x0B] << 8)), (unsigned int)(edid[0x0C] + (edid[0x0D] << 8) + (edid[0x0E] << 16) + (edid[0x0F] << 24))); /* XXX need manufacturer ID table */ if (edid[0x10] < 55 || edid[0x10] == 0xff) { c.has_valid_week = 1; if (edid[0x11] > 0x0f) { if (edid[0x10] == 0xff) { c.has_valid_year = 1; printk(BIOS_SPEW, "Made week %hhd of model year %hhd\n", edid[0x10], edid[0x11]); extra_info.week = edid[0x10]; extra_info.year = edid[0x11]; } else { /* we know it's at least 2013, when this code * was written */ if (edid[0x11] + 90 <= 2013) { c.has_valid_year = 1; printk(BIOS_SPEW, "Made week %hhd of %d\n", edid[0x10], edid[0x11] + 1990); extra_info.week = edid[0x10]; extra_info.year = edid[0x11] + 1990; } } } } printk(BIOS_SPEW, "EDID version: %hhd.%hhd\n", edid[0x12], edid[0x13]); extra_info.version[0] = edid[0x12]; extra_info.version[1] = edid[0x13]; if (edid[0x12] == 1) { if (edid[0x13] > 4) { printk(BIOS_SPEW, "Claims > 1.4, assuming 1.4 conformance\n"); edid[0x13] = 4; } switch (edid[0x13]) { case 4: c.claims_one_point_four = 1; __fallthrough; case 3: c.claims_one_point_three = 1; __fallthrough; case 2: c.claims_one_point_two = 1; __fallthrough; default: c.claims_one_point_oh = 1; } } /* display section */ if (edid[0x14] & 0x80) { int conformance_mask; analog = 0; printk(BIOS_SPEW, "Digital display\n"); if (c.claims_one_point_four) { conformance_mask = 0; if ((edid[0x14] & 0x70) == 0x00) printk(BIOS_SPEW, "Color depth is undefined\n"); else if ((edid[0x14] & 0x70) == 0x70) c.nonconformant_digital_display = 1; else printk(BIOS_SPEW, "%d bits per primary color channel\n", ((edid[0x14] & 0x70) >> 3) + 4); out->panel_bits_per_color = ((edid[0x14] & 0x70) >> 3) + 4; out->panel_bits_per_pixel = 3*out->panel_bits_per_color; switch (edid[0x14] & 0x0f) { case 0x00: printk(BIOS_SPEW, "Digital interface is not defined\n"); break; case 0x01: printk(BIOS_SPEW, "DVI interface\n"); break; case 0x02: printk(BIOS_SPEW, "HDMI-a interface\n"); break; case 0x03: printk(BIOS_SPEW, "HDMI-b interface\n"); break; case 0x04: printk(BIOS_SPEW, "MDDI interface\n"); break; case 0x05: printk(BIOS_SPEW, "DisplayPort interface\n"); break; default: c.nonconformant_digital_display = 1; break; } extra_info.type = edid[0x14] & 0x0f; } else if (c.claims_one_point_two) { conformance_mask = 0x7E; if (edid[0x14] & 0x01) printk(BIOS_SPEW, "DFP 1.x compatible TMDS\n"); } else conformance_mask = 0x7F; if (!c.nonconformant_digital_display) c.nonconformant_digital_display = edid[0x14] & conformance_mask; extra_info.nonconformant = c.nonconformant_digital_display; } else { analog = 1; int voltage = (edid[0x14] & 0x60) >> 5; int sync = (edid[0x14] & 0x0F); extra_info.voltage = voltage; extra_info.sync = sync; printk(BIOS_SPEW, "Analog display, Input voltage level: %s V\n", voltage == 3 ? "0.7/0.7" : voltage == 2 ? "1.0/0.4" : voltage == 1 ? "0.714/0.286" : "0.7/0.3"); if (c.claims_one_point_four) { if (edid[0x14] & 0x10) printk(BIOS_SPEW, "Blank-to-black setup/pedestal\n"); else printk(BIOS_SPEW, "Blank level equals black level\n"); } else if (edid[0x14] & 0x10) { /* * XXX this is just the X text. 1.3 says "if set, * display expects a blank-to-black setup or pedestal * per appropriate Signal Level Standard". Whatever * _that_ means. */ printk(BIOS_SPEW, "Configurable signal levels\n"); } printk(BIOS_SPEW, "Sync: %s%s%s%s\n", sync & 0x08 ? "Separate " : "", sync & 0x04 ? "Composite " : "", sync & 0x02 ? "SyncOnGreen " : "", sync & 0x01 ? "Serration " : ""); } if (edid[0x15] && edid[0x16]) { printk(BIOS_SPEW, "Maximum image size: %d cm x %d cm\n", edid[0x15], edid[0x16]); } else if (c.claims_one_point_four && (edid[0x15] || edid[0x16])) { if (edid[0x15]) { /* edid[0x15] != 0 && edid[0x16] == 0 */ unsigned int ratio = 100000/(edid[0x15] + 99); printk(BIOS_SPEW, "Aspect ratio is %u.%03u (landscape)\n", ratio / 1000, ratio % 1000); } else { /* edid[0x15] == 0 && edid[0x16] != 0 */ unsigned int ratio = 100000/(edid[0x16] + 99); printk(BIOS_SPEW, "Aspect ratio is %u.%03u (portrait)\n", ratio / 1000, ratio % 1000); } } else { /* Either or both can be zero for 1.3 and before */ printk(BIOS_SPEW, "Image size is variable\n"); } if (edid[0x17] == 0xff) { if (c.claims_one_point_four) printk(BIOS_SPEW, "Gamma is defined in an extension block\n"); else /* XXX Technically 1.3 doesn't say this... */ printk(BIOS_SPEW, "Gamma: 1.0\n"); } else printk(BIOS_SPEW, "Gamma: %d%%\n", ((edid[0x17] + 100))); printk(BIOS_SPEW, "Check DPMS levels\n"); if (edid[0x18] & 0xE0) { printk(BIOS_SPEW, "DPMS levels:"); if (edid[0x18] & 0x80) printk(BIOS_SPEW, " Standby"); if (edid[0x18] & 0x40) printk(BIOS_SPEW, " Suspend"); if (edid[0x18] & 0x20) printk(BIOS_SPEW, " Off"); printk(BIOS_SPEW, "\n"); } /* FIXME: this is from 1.4 spec, check earlier */ if (analog) { switch (edid[0x18] & 0x18) { case 0x00: printk(BIOS_SPEW, "Monochrome or grayscale display\n"); break; case 0x08: printk(BIOS_SPEW, "RGB color display\n"); break; case 0x10: printk(BIOS_SPEW, "Non-RGB color display\n"); break; case 0x18: printk(BIOS_SPEW, "Undefined display color type\n"); break; } } else { printk(BIOS_SPEW, "Supported color formats: RGB 4:4:4"); if (edid[0x18] & 0x10) printk(BIOS_SPEW, ", YCrCb 4:4:4"); if (edid[0x18] & 0x08) printk(BIOS_SPEW, ", YCrCb 4:2:2"); printk(BIOS_SPEW, "\n"); } if (edid[0x18] & 0x04) printk(BIOS_SPEW, "Default (sRGB) color space is primary color space\n"); if (edid[0x18] & 0x02) { printk(BIOS_SPEW, "First detailed timing is preferred timing\n"); c.has_preferred_timing = 1; } if (edid[0x18] & 0x01) printk(BIOS_SPEW, "Supports GTF timings within operating range\n"); /* XXX color section */ printk(BIOS_SPEW, "Established timings supported:\n"); /* it's not yet clear we want all this stuff in the edid struct. * Let's wait. */ for (i = 0; i < 17; i++) { if (edid[0x23 + i / 8] & (1 << (7 - i % 8))) { printk(BIOS_SPEW, " %dx%d@%dHz\n", established_timings[i].x, established_timings[i].y, established_timings[i].refresh); for (j = 0; j < NUM_KNOWN_MODES; j++) { if (known_modes[j].ha == established_timings[i].x && known_modes[j].va == established_timings[i].y && known_modes[j].refresh == established_timings[i].refresh) out->mode_is_supported[j] = 1; } } } printk(BIOS_SPEW, "Standard timings supported:\n"); for (i = 0; i < 8; i++) { uint8_t b1 = edid[0x26 + i * 2], b2 = edid[0x26 + i * 2 + 1]; unsigned int x, y = 0, refresh; if (b1 == 0x01 && b2 == 0x01) continue; if (b1 == 0) { printk(BIOS_SPEW, "non-conformant standard timing (0 horiz)\n"); continue; } x = (b1 + 31) * 8; switch ((b2 >> 6) & 0x3) { case 0x00: if (c.claims_one_point_three) y = x * 10 / 16; else y = x; break; case 0x01: y = x * 3 / 4; break; case 0x02: y = x * 4 / 5; break; case 0x03: y = x * 9 / 16; break; } refresh = 60 + (b2 & 0x3f); printk(BIOS_SPEW, " %dx%d@%dHz\n", x, y, refresh); for (j = 0; j < NUM_KNOWN_MODES; j++) { if (known_modes[j].ha == x && known_modes[j].va == y && known_modes[j].refresh == refresh) out->mode_is_supported[j] = 1; } } /* detailed timings */ printk(BIOS_SPEW, "Detailed timings\n"); for (i = 0; i < 4; i++) { c.has_valid_detailed_blocks &= detailed_block( out, edid + 0x36 + i * 18, 0, &c); if (i == 0 && c.has_preferred_timing && !c.did_detailed_timing) { /* not really accurate... */ c.has_preferred_timing = 0; } } /* check this, 1.4 verification guide says otherwise */ if (edid[0x7e]) { printk(BIOS_SPEW, "Has %d extension blocks\n", edid[0x7e]); /* 2 is impossible because of the block map */ if (edid[0x7e] != 2) c.has_valid_extension_count = 1; } else { c.has_valid_extension_count = 1; } printk(BIOS_SPEW, "Checksum\n"); c.has_valid_checksum = do_checksum(edid); /* EDID v2.0 has a larger blob (256 bytes) and may have some problem in * the extension parsing loop below. Since v2.0 was quickly deprecated * by v1.3 and we are unlikely to use any EDID 2.0 panels, we ignore * that case now and can fix it when we need to use a real 2.0 panel. */ for (i = 128; i < size; i += 128) c.nonconformant_extension += parse_extension(out, &edid[i], &c); if (c.claims_one_point_four) { if (c.nonconformant_digital_display || !c.has_valid_string_termination || !c.has_valid_descriptor_pad || !c.has_preferred_timing) { c.conformant = EDID_NOT_CONFORMANT; printk(BIOS_ERR, "EDID block does NOT conform to EDID 1.4!\n"); } if (c.nonconformant_digital_display) printk(BIOS_ERR, "\tDigital display field contains garbage: %x\n", c.nonconformant_digital_display); if (!c.has_valid_string_termination) printk(BIOS_ERR, "\tDetailed block string not properly terminated\n"); if (!c.has_valid_descriptor_pad) printk(BIOS_ERR, "\tInvalid descriptor block padding\n"); if (!c.has_preferred_timing) printk(BIOS_ERR, "\tMissing preferred timing\n"); } else if (c.claims_one_point_three) { if (c.nonconformant_digital_display || !c.has_valid_string_termination || !c.has_valid_descriptor_pad || !c.has_preferred_timing) { c.conformant = EDID_NOT_CONFORMANT; } /** * According to E-EDID (EDIDv1.3), has_name_descriptor and * has_range_descriptor are both required. These fields are * optional in v1.4. However some v1.3 panels (Ex, B133XTN01.3) * don't have them. As a workaround, we only print warning * messages. */ if (c.conformant == EDID_NOT_CONFORMANT) printk(BIOS_ERR, "EDID block does NOT conform to EDID 1.3!\n"); else if (!c.has_name_descriptor || !c.has_range_descriptor) printk(BIOS_WARNING, "EDID block does NOT " "fully conform to EDID 1.3.\n"); if (c.nonconformant_digital_display) printk(BIOS_ERR, "\tDigital display field contains garbage: %x\n", c.nonconformant_digital_display); if (!c.has_name_descriptor) printk(BIOS_ERR, "\tMissing name descriptor\n"); if (!c.has_preferred_timing) printk(BIOS_ERR, "\tMissing preferred timing\n"); if (!c.has_range_descriptor) printk(BIOS_ERR, "\tMissing monitor ranges\n"); /* Might be more than just 1.3 */ if (!c.has_valid_descriptor_pad) printk(BIOS_ERR, "\tInvalid descriptor block padding\n"); if (!c.has_valid_string_termination) /* Likewise */ printk(BIOS_ERR, "\tDetailed block string not properly terminated\n"); } else if (c.claims_one_point_two) { if (c.nonconformant_digital_display || !c.has_valid_string_termination) { c.conformant = EDID_NOT_CONFORMANT; printk(BIOS_ERR, "EDID block does NOT conform to EDID 1.2!\n"); } if (c.nonconformant_digital_display) printk(BIOS_ERR, "\tDigital display field contains garbage: %x\n", c.nonconformant_digital_display); if (!c.has_valid_string_termination) printk(BIOS_ERR, "\tDetailed block string not properly terminated\n"); } else if (c.claims_one_point_oh) { if (c.seen_non_detailed_descriptor) { c.conformant = EDID_NOT_CONFORMANT; printk(BIOS_ERR, "EDID block does NOT conform to EDID 1.0!\n"); } if (c.seen_non_detailed_descriptor) printk(BIOS_ERR, "\tHas descriptor blocks other than detailed timings\n"); } if (c.nonconformant_extension || !c.has_valid_checksum || !c.has_valid_cvt || !c.has_valid_year || !c.has_valid_week || !c.has_valid_detailed_blocks || !c.has_valid_dummy_block || !c.has_valid_extension_count || !c.has_valid_descriptor_ordering || !c.has_valid_range_descriptor || !c.manufacturer_name_well_formed) { c.conformant = EDID_NOT_CONFORMANT; printk(BIOS_ERR, "EDID block does not conform at all!\n"); if (c.nonconformant_extension) printk(BIOS_ERR, "\tHas %d nonconformant extension block(s)\n", c.nonconformant_extension); if (!c.has_valid_checksum) printk(BIOS_ERR, "\tBlock has broken checksum\n"); if (!c.has_valid_cvt) printk(BIOS_ERR, "\tBroken 3-byte CVT blocks\n"); if (!c.has_valid_year) printk(BIOS_ERR, "\tBad year of manufacture\n"); if (!c.has_valid_week) printk(BIOS_ERR, "\tBad week of manufacture\n"); if (!c.has_valid_detailed_blocks) printk(BIOS_ERR, "\tDetailed blocks filled with garbage\n"); if (!c.has_valid_dummy_block) printk(BIOS_ERR, "\tDummy block filled with garbage\n"); if (!c.has_valid_extension_count) printk(BIOS_ERR, "\tImpossible extension block count\n"); if (!c.manufacturer_name_well_formed) printk(BIOS_ERR, "\tManufacturer name field contains garbage\n"); if (!c.has_valid_descriptor_ordering) printk(BIOS_ERR, "\tInvalid detailed timing descriptor ordering\n"); if (!c.has_valid_range_descriptor) printk(BIOS_ERR, "\tRange descriptor contains garbage\n"); if (!c.has_valid_max_dotclock) printk(BIOS_ERR, "\tEDID 1.4 block does not set max dotclock\n"); } if (c.warning_excessive_dotclock_correction) printk(BIOS_ERR, "Warning: CVT block corrects dotclock by more than 9.75MHz\n"); if (c.warning_zero_preferred_refresh) printk(BIOS_ERR, "Warning: CVT block does not set preferred refresh rate\n"); return c.conformant; } /* * Notes on panel extensions: (TODO, implement me in the code) * * EPI: http://www.epi-standard.org/fileadmin/spec/EPI_Specification1.0.pdf * at offset 0x6c (fourth detailed block): (all other bits reserved) * 0x6c: 00 00 00 0e 00 * 0x71: bit 6-5: data color mapping (00 conventional/fpdi/vesa, 01 openldi) * bit 4-3: pixels per clock (00 1, 01 2, 10 4, 11 reserved) * bit 2-0: bits per pixel (000 18, 001 24, 010 30, else reserved) * 0x72: bit 5: FPSCLK polarity (0 normal 1 inverted) * bit 4: DE polarity (0 high active 1 low active) * bit 3-0: interface (0000 LVDS TFT * 0001 mono STN 4/8bit * 0010 color STN 8/16 bit * 0011 18 bit tft * 0100 24 bit tft * 0101 tmds * else reserved) * 0x73: bit 1: horizontal display mode (0 normal 1 right/left reverse) * bit 0: vertical display mode (0 normal 1 up/down reverse) * 0x74: bit 7-4: total poweroff seq delay (0000 vga controller default * else time in 10ms (10ms to 150ms)) * bit 3-0: total poweron seq delay (as above) * 0x75: contrast power on/off seq delay, same as 0x74 * 0x76: bit 7: backlight control enable (1 means this field is valid) * bit 6: backlight enabled at boot (0 on 1 off) * bit 5-0: backlight brightness control steps (0..63) * 0x77: bit 7: contrast control, same bit pattern as 0x76 except bit 6 resvd * 0x78 - 0x7c: reserved * 0x7d: bit 7-4: EPI descriptor major version (1) * bit 3-0: EPI descriptor minor version (0) * * ---- * * SPWG: http://www.spwg.org/spwg_spec_version3.8_3-14-2007.pdf * * Since these are "dummy" blocks, terminate with 0a 20 20 20 ... as usual * * detailed descriptor 3: * 0x5a - 0x5e: 00 00 00 fe 00 * 0x5f - 0x63: PC maker part number * 0x64: LCD supplier revision # * 0x65 - 0x6b: manufacturer part number * * detailed descriptor 4: * 0x6c - 0x70: 00 00 00 fe 00 * 0x71 - 0x78: smbus nits values (whut) * 0x79: number of lvds channels (1 or 2) * 0x7A: panel self test (1 if present) * and then dummy terminator * * SPWG also says something strange about the LSB of detailed descriptor 1: * "LSB is set to "1" if panel is DE-timing only. H/V can be ignored." */ /* Set the framebuffer bits-per-pixel, recalculating all dependent values. */ void edid_set_framebuffer_bits_per_pixel(struct edid *edid, int fb_bpp, int row_byte_alignment) { /* Caller should pass a supported value, everything else is BUG(). */ assert(fb_bpp == 32 || fb_bpp == 24 || fb_bpp == 16); row_byte_alignment = MAX(row_byte_alignment, 1); edid->framebuffer_bits_per_pixel = fb_bpp; edid->bytes_per_line = ALIGN_UP(edid->mode.ha * DIV_ROUND_UP(fb_bpp, 8), row_byte_alignment); edid->x_resolution = edid->bytes_per_line / (fb_bpp / 8); edid->y_resolution = edid->mode.va; }